Spacer unit for use in a movable joint of a prosthetic or orthopedic system

ABSTRACT

A prosthetic system includes a movable joint defining at least one gap, and at least one spacer unit positionable in the at least one gap. The at least one spacer unit includes a resilient element that is controllably deformable to vary a thickness of the at least one spacer unit to fill the at least one gap, and to reduce the likelihood of the at least one spacer unit interfering with relative movement between components of the movable joint. The at least one material forming the resilient element is compressible in a first direction with little or no expansion in a second direction normal to the first direction.

TECHNICAL FIELD

The disclosure pertains to components used in joints of prostheticand/or orthopedic systems.

BACKGROUND

Many conventional orthopedic and prosthetic systems require at least onemovable joint for controlling, supporting, immobilizing, replacing, ortreating muscles, joints, or skeletal parts, which are weak,ineffective, deformed, missing, or injured. Movable joints are generallydesigned to allow relative movement between components of a system inone or more degrees of freedom, and restrict movement in one or moreothers (e.g., a pivot point, an axle connection, a sliding connection).Such movable joints can be found in prosthetic knees, prosthetic feet,prosthetic shock absorbers, and many other types of prosthetic andorthopedic systems.

Usually a gap is present between the components forming the movablejoint that receives a metal or plastic washer. This gap unfortunately isknown to vary in size because of manufacturing differences in thecomponents (e.g., +/− about 0.5 mm). Also, washer size regularly variesfrom one washer to another. These types of inconsistencies from movablejoint to movable joint and washer to washer can be problematic for manyreasons. For instance, if the gap is too small or the washer is too big,the washer may require permanent alterations such as grinding or cuttingto fit the washer in the gap. If the gap is too big or the washer is toosmall, additional washers of varying sizes may be required and/orpermanent alterations of the washers may be required to effectivelybring the fit of the washers in the gap within acceptable tolerances.

Modifying washers (e.g., via grinding) and custom fitting differentnumbers of washers between the components are labor-intensive andtime-consuming activities prone to inconsistencies and error. Inaddition, contact between the components and a metal or plastic washerduring movement of the movable joint may produce an undesirablestick-slip effect and/or sudden movements in the movable joint,negatively impacting the performance of the movable joint and increasingthe likelihood of injury or patient dissatisfaction.

There is thus a need to simplify the assembly of movable joints inprosthetic and orthopedic systems and to improve their performance.

SUMMARY

The disclosure describes various embodiments of a spacer unit for use ina movable joint of a prosthetic or orthopedic system which overcomes theproblems mentioned above by reducing free play, providing axial andradial damping, and facilitating easier assembly.

According to an embodiment, a spacer unit is positionable in a gapdefined within a movable joint. The spacer unit includes a resilientelement formed of at least one material that is controllably deformableto vary a thickness of the at least one spacer unit to fill the at leastone gap. The at least one material can be compressible in a firstdirection with little or no expansion in a second direction normal tothe first direction. This helps to avoid the potential drawbacks of theresilient element expanding radially under compression and interferingwith the proper movement of the movable joint. It also helps to quicklyand easily fit the spacer unit in the gap, facilitating assembly of themovable joint. This is advantageous over known movable joints as rigidwashers customarily positioned in gaps tend to vary in size because ofmanufacturing imperfections, resulting often in the costly andlabor-intensive process of grinding excess material from the washers, oradding additional washers to fill the gap.

In addition, the controlled deformation of the resilient element canprovide an axial resistance within the gap to help space components ofthe movable joint. It can also dynamically reduce axial play between thecomponents during use of the movable joint as the thickness of thespacer unit changes with the size of the gap while helping to maintainthe components apart. The resilient element also can provide an amountof torsional damping as the components rotate relative to one another,making the operation of the movable joint feel more natural or smooth.Moreover, deformation of the resilient element within the gap can helpabsorb energy if lateral or medial forces are generated in the movablejoint, offering an amount of axial damping.

Further, the resilient element may also help to reduce and mitigatestick/slip effects between metal components and reduce “free play”effects between components of the movable joint.

According to a variation, the spacer unit includes at least one rigidelement that forms a bearing surface between the spacer unit and themovable joint. This beneficially allows the spacer unit to compress anddistribute loads in the gap while the at least one rigid element directsforces away from the resilient element, reducing wear and tear on thespacer unit. The at least one rigid element may be formed of metaland/or a plastic material that helps direct forces away from theresilient element and allows the resilient element to compress andabsorb differences or changes in the size of the gap.

According to other embodiments of the spacer unit, spacer units maycomprise numerous variations and configurations of rigid elementsarranged with resilient elements to provide damping, force distribution,operational advantages, and easier assembly in different prosthetic andorthopedic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood regarding the followingdescription, appended claims, and accompanying drawings.

FIG. 1 is a perspective view of a prosthetic device including a movablejoint according to an embodiment.

FIG. 2 is a schematic cross section of the movable joint in FIG. 1.

FIG. 3 is a schematic cross section of the movable joint in FIG. 1 in aloaded and unloaded configuration.

FIG. 4 is a schematic cross-section of a spacer unit according toanother embodiment.

FIG. 5 is a schematic cross-section of a spacer unit according toanother embodiment.

FIG. 6 is a schematic cross-section of a spacer unit according toanother embodiment.

FIG. 7 is a side view of a spacer unit according to another embodiment.

FIG. 8 is a side view of a spacer unit according to another embodiment.

FIG. 9 is a side view of a spacer unit according to another embodiment.

FIG. 10 is a perspective view of a prosthetic device including a movablejoint according to another embodiment.

FIG. 11 is a cross-section of a movable joint in FIG. 10.

FIG. 12 is a partial exploded view of the movable joint in FIG. 1.

FIG. 13 is a perspective view of a prosthetic device including a movablejoint according to another embodiment.

FIG. 14 is a cross-section of the prosthetic device in FIG. 13.

FIG. 15 is a perspective view of a movable joint according to anotherembodiment.

FIG. 16A is a cross section of the movable joint in FIG. 15.

FIG. 16B is another cross-section of the movable joint in FIG. 15.

FIG. 17 is a side view of the spacer unit in FIG. 16A.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

A better understanding of different embodiments of the disclosure may behad from the following description read with the accompanying drawingsin which like reference characters refer to like elements.

While the disclosure is susceptible to various modifications andalternative constructions, certain illustrative embodiments are in thedrawings and are described below. It should be understood, however,there is no intention to limit the disclosure to the specificembodiments disclosed, but on the contrary, the aim covers allmodifications, alternative constructions, combinations, and equivalentsfalling within the spirit and scope of the disclosure.

It will be understood that unless a term is expressly defined in thisapplication to possess a described meaning, there is no intent to limitthe meaning of such term, either expressly or indirectly, beyond itsplain or ordinary meaning. Any element in a claim that does notexplicitly state “means for” performing a specified function, or “stepfor” performing a specific function is not to be interpreted as a“means” or “step” clause as specified in 35 U.S.C. § 112(f).

Embodiments of the present disclosure include a spacer unit for use witha movable joint that simplifies assembly of a movable joint in aprosthetic or orthopedic system and can improve its performance. Thespacer unit includes a resilient element formed of at least one materialthat is controllably deformable within a gap defined within the movablejoint to effectively fill the gap. The at least one material can becompressible in a first direction with little or no expansion in asecond direction normal to the first direction. This can provide anaxial resistance within the gap arranged to help space components of themovable joint, reducing axial play between the components of the movablejoint and the reducing likelihood of the spacer unit interfering withrelative movement between components of the movable joint. The resilientelement can also dynamically reduce axial play between the componentsduring use of the movable joint as the thickness of the spacer unitchanges with the size of the gap while helping to maintain thecomponents apart. Moreover, deformation of the resilient element withinthe gap can absorb energy if lateral or medial forces are generated inthe movable joint, offering an amount of axial damping. It also canprovide an amount of torsional damping as the components rotatedrelative to one another, making the movement of the movable joint feelmore natural or smooth.

The spacer unit embodiments described are configured for use withmovable joints including a prosthetic knee, a prosthetic foot, aprosthetic shock absorber, and a bearing for a prosthetic device. Itshould be remembered, however, that the same concepts and methodsdescribed may be similarly used for other prosthetic and orthopedicsystems.

As shown in FIG. 1, embodiments of the spacer unit can be employed withat least one movable joint 100 of a prosthetic system 10. The prostheticsystem 10 is shown as a prosthetic knee but can be any suitableprosthetic or orthopedic system. The movable joint 100 can include firstand second components 102, 104 which are arranged to rotate relative toone another about at least one pivot point 106. It will be appreciatedthat both or one of the components 102, 104 may be arranged to rotateabout the pivot point 106. The pivot point 106 is shown being defined byan axle 108 extending through the first and second components 102, 104.

FIG. 2 is a schematic cross section of the movable joint 100 of FIG. 1.A gap G is defined between the first component 102 and the secondcomponent 104 along a length of the axle 108. A spacer unit 110 isreceived in the gap G between the first and second parts 102, 104. Thespacer unit 110 includes a body having a resilient element 111 formed ofa material arranged to resiliently deform or compress and expand in adirection along the axle 108. The spacer unit 110 can thus axiallycompress or expand to controllably vary a thickness T of the spacer unit110 to fit the gap G and other gaps having differing sizes withoutlabor- and cost-intensive grinding and/or other adjustments. The spacerunit 110 further can provide axial resistance arranged to help space thefirst component 102 from the second component 104.

If the gap G is smaller, the spacer unit 110 can compress more axiallyto fill the gap G. If the gap G is larger, the spacer unit 110 cancompress less axially or compress and then expand axially to fill thegap G. This beneficially allows the spacer unit 110 to accommodate orabsorb differences in gap widths or sizes without having to modifywashers or add more washers in the gap as in the prior art, providing asimpler and less labor-intensive assembly of the movable joint 100. Thethickness T of the spacer unit 110 can be variable during the use of themovable joint 100. For instance, it can dynamically reduce axial playbetween the first and second components 102, 104 during use of themovable joint 100 as the thickness T of the spacer unit 110 changes withthe gap size while helping to maintain the first and second components102, 104 apart. In an embodiment, the spacer unit 110 can be arranged toresiliently compress and/or expand between about 1% and about 80% in theaxial direction. For instance, when compressed in the movable joint 100,the thickness T or length of the spacer unit 110 along an axis 113 canbe arranged to be about 95%, about 90%, about 85%, or about 80% of itsoriginal thickness T or length. In other words, the thickness T orlength of the spacer unit 110 along the axis 113 can be arranged toreduce by about 5%, about 10%, about 15%, or about 20% when the spacerunit 110 is compressed in the movable joint 100.

The compression and/or pre-compression of the resilient element 111 isat least in part dependent on stiffness and/or density of the materialincluded in the resilient element 111 and can vary for different typesof material. As such, different materials forming the resilient element111 can be selected to achieve the desired compression of the spacerunit 110 for specific applications. For example, a denser foam materialor elastomer material can be selected such that the spacer unit 110exhibits less compression in the axial direction, which, in turn,increases the resistance of the spacer unit 110 to relative movementbetween the first and second components 102, 104. Or, a less stiff foammaterial or elastomer material can be selected such that the spacer unit110 exhibits more compression in the axial direction.

In addition to overcoming free play between the components 102, 104, thespacer unit 110 may provide an amount of axial damping to the movablejoint 100. By way of example, when the movable joint 100 is loadedaxially, the resilient element 111 can deform between the first andsecond components 102, 104 to extract mechanical energy from axialmovement between the first and second components 102, 104, which, inturn, provides an amount of axial damping in the movable joint 100.

The spacer unit 110 may also provide an amount of torsional damping tothe prosthetic system 10. The resilient element 111 can be twistable ina gap G1 located between first and second components 102, 104 to providean amount of torsional damping during use of the movable joint 100. Whenthere is relative rotation between the first and second components 102,104, at least part of the resilient element 111 can resiliently twistand deform to extract mechanical energy from the rotational movementbetween the first and second components 102, 104, which, in turn,provides an amount of torsional damping in the movable joint 100. Suchdamping from the spacer unit 110 can enhance user comfort and safety andhelps the movement of the movable joint 100 feel more natural. In anembodiment, the amount of damping provided by the spacer unit 110 can becontrolled by the size and/or material of the spacer unit 110. Forinstance, an increase in the thickness T of the spacer unit 110 or aselected material forming the resilient element 111 can provide agreater amount of axial damping. According to a variation, the resilientelement 111 is arranged to provide an amount of controlled resistance torotation between the first and second components 102, 104, helping tocontrol the movement of the prosthetic system 10. The first component102 can be a housing or upper knee part and the second component 104 canbe at least one link connecting the first component 102 to a chassis orlower knee part.

In an embodiment, the resilient element 111 includes an anisotropicmaterial arranged to resiliently compress in the first direction (e.g.,axial direction) with little or no change in shape in the seconddirection (e.g., radial direction). The spacer unit 110 can thus bearranged for applications where the surrounding space is confined orwhere the spacer unit 110 is located within an enclosure or groove. Forinstance, the spacer unit 110 can be received in the gap G1 within abushing or sleeve 112 as shown in FIG. 3. The anisotropic material ofthe resilient element 111 can be a resiliently compressible material, afoam material, an open-celled material, an elastomer material,combinations thereof, or any other suitable anisotropic material. Theanisotropic material is preferably a polyurethane foam material such asCellasto from BASF.

When the first and second components 102, 104 are loaded axially, thespacer unit 110 can be compressed between the first and secondcomponents 102, 104 as the gap G1 is reduced to gap G2, having a smallersize. As the spacer unit 110 is axially compressed, the diameter D orradial dimension of the spacer unit 110 can be substantially unchanged.When the first and second components 102, 104 are unloaded axially,stored energy in the resilient element 111 can cause the spacer unit 110to expand axially between the first and second components 102, 104without substantially changing shape in a radial direction as the gap G2returns toward the gap G1. This permits the spacer unit 110 to absorbdifferences or changes in gap sizes and reduce free play between thecomponents 102, 104 without engaging or interfering with the sleeve orbushing 112 in the radial direction, improving performance and safety ofthe movable joint 100. In an embodiment, the spacer unit 110 is arrangedto compress and/or expand between about 10% and about 25% (e.g., 20%) orbetween about 15% and about 20% in the axial direction withoutsubstantially changing shape in a radial direction.

It will be appreciated that the spacer unit of the present disclosure isadvantageous over known movable joints in prosthetic systems that haveattempted to use elastomeric washers in gaps between joint components.Such washers exhibit relatively large radial expansion when compressedand are thus prone to engage and interfere with the movable joint in theradial direction. This detrimentally can cause the movable joint to bindor fail and presents a serious threat of injury to a user.

The advantages described above are only some of those provided by thespacer unit of the present disclosure. For example, the spacer unit 110can have a lightweight and durable configuration, reducing the overallweight and increasing the overall durability of the prosthetic system10. In other embodiments, the spacer unit 110 can also reduce thelikelihood of a slip-stick effect in the movable joint 100. Slip-stickeffect is generally the spontaneous jerking motion that can occur whiletwo components slide over each other. In the movable joint 100, thestatic coefficient of friction between a rigid washer (metal andplastic) and at least one of the components 102, 104 can be greater thanthe kinetic coefficient of friction. If a rotational force between thewasher and component is large enough to overcome the static friction,then the reduction of the friction to the kinetic friction can cause asudden jump in the velocity of the movement, which can be highlydisruptive to a user when walking or standing.

When the spacer unit 110 is used in the movable joint 100, thedifferential between the static and kinetic coefficients at theinterface between the resilient element 111 of the spacer unit 110 andat least one of the components 102, 104 can be less than between aplastic or metal washer and the components 102, 104. As a result, whenat least one of the components 102, 104 rotate over the spacer unit 110,the friction reduction therebetween is less, which, in turn, reduces thelikelihood and magnitude of a sudden increase in velocity of the firstcomponent 102 and/or the second component 104. Moreover, when at leastone of the first and second components 102, 104 rotates over the spacerunit 110, the resilient element 111 can twist and rotate with the atleast one of the components 102, 104, reducing the slip-stick effect inthe movable joint 100. In other embodiments, the resilient element 111can reduce vibrations within the movable joint 100.

According to a variation, the resilient element is formed of a foammaterial such as a polyurethane foam or an open-celled material. Theresilient element 111 can include a heat formable material. In otherembodiments, the resilient element 111 can include ethylene-vinylacetate (EVA) foam and/or thermoplastic elastomers (TPE). The resilientelement 111 can include an elastomeric material. The materials andconstruction of the spacer unit described are to be regarded asexemplary only, as any suitable materials and/or properties that canstructurally fill the gap and dampen the movable joint may beenvisioned.

FIG. 4 shows a spacer unit 210 according to another embodiment. Thespacer unit 210 includes at least one rigid element 220 and a resilientelement 222 resiliently compressible and expandable to controllably varya thickness of the spacer unit 210 to fit the gap of a movable joint.The spacer unit 210 also can provide an axial resistance arranged tohelp space a first component of the movable joint from a secondcomponent. In an embodiment, the resilient element 222 includes ananisotropic material that can resiliently compress in the firstdirection (e.g., axial direction) with little or no change in shape inthe second direction (e.g., radial direction). This beneficially permitsthe spacer unit 210 to absorb differences or changes in gap size withoutinterfering with a movable joint in a radial direction. The anisotropicmaterial can comprise a polyurethane foam material.

The resilient element 222 and the at least one rigid element 220 can bein a stacked configuration. For instance, the at least one rigid element220 can comprise a pair of outer rigid elements 220 and the resilientelement 222 can be located between the outer rigid elements 220. Theresilient element 222 may be fixedly attached to the outer rigidelements 220 or the resilient element 222 may be connected to the outerrigid elements 220 such that some degree of relative movement is allowedbetween the resilient element 222 and the outer rigid elements 220. Theouter rigid elements 220 can have the same or different thicknesses. Atleast one of the outer rigid elements 220 can have a substantially sameshape of the resilient element 222.

In use, the outer rigid elements 220 can form bearing surfaces betweenthe spacer unit 210 and components of the movable joint and theresilient element 222 can resiliently compress between the outer rigidelements 220 to absorb differences or changes in gap sizes and reducefree play between the components of the movable joint. This allows thespacer unit 210 to compress and distribute loads in the gap, reducingwear and tear on the spacer unit 210. For instance, the outer rigidelements 220 direct forces away from the resilient element 222 while theresilient element 222 dampens axial and torsional movement of themovable joint and reduces free play between the components.

FIG. 5 shows a spacer unit 310 according to another embodiment includinga rigid element 320 and a resilient element 322 resiliently compressibleand expandable to controllably vary a thickness of the spacer unit 310to fill or fit the gap of a movable joint. The resilient element 322 mayinclude an anisotropic material arranged to resiliently compress in thefirst direction (e.g., axial direction) with little or no change inshape in the second direction (e.g., radial direction).

The resilient element 322 defines a first surface attached to the rigidelement 320 and a second surface arranged to interact with the movablejoint. This allows the rigid element 320 to distribute loads away fromthe resilient element 322 and the resilient element 322 to reducestick-slip motion in the movable joint. The rigid element 320 and theresilient element 322 can have the same or different diameters orlateral dimensions. The rigid element 320 and the resilient element canhave a substantially same shape.

FIG. 6 shows a spacer unit 410 according to yet another embodiment. Thespacer unit 410 includes a rigid element 420, a first resilient element422 attached to the rigid element 420 and including a first anisotropicmaterial, and a second resilient element 424 attached to the firstresilient element 422 and including a second anisotropic material. Thefirst and second resilient elements 422, 424 can have a same ordifferent thickness. The first and second anisotropic materials can bedifferent materials. The first and second anisotropic materials can be afoam material, TPE, EVA, or any other suitable material. The resiliency,resistance, compressibility, and/or other properties of the spacer unit410 may vary from resilient element to resilient element. Differencesbetween the first and second resilient elements 422, 424 can be selectedto vary their characteristics during movement of the movable joint. Forinstance, the first and second resilient elements 422, 424 can bearranged to compress or deform differently or progressively underdifferent conditions.

Spacer unit embodiments described herein can be in any suitable form foruse in a movable joint. For instance, FIG. 7 shows a spacer unit 510having an annular shape defining a central opening 512 for receiving anaxle, shaft, or pin of a movable joint. FIG. 8 shows a spacer unit 610in the form of a strip element. The spacer unit 610 can be wrapped orextended around an axle, shaft, or pin in a gap. FIG. 9 shows a spacerunit 710 having a C-shape that can be slid onto an axle, a shaft, or apin from a radial direction.

FIGS. 10 and 11 illustrate a prosthetic system 20 according to anotherembodiment comprising a prosthetic foot 21 including a plurality ofmovable joints with at least one spacer unit 810. The prosthetic foot 21has an ankle unit 22. The ankle unit 22 is pivotally connected to a footelement 24 at a first movable joint 800A along the front of the ankleunit 22 and to a connection member 26 at a second movable joint 800Bthat is located at a rear portion of the prosthetic foot 21.

The connection member 26 is connected to a rear of the foot element 24at a third movable joint 800C and connects the ankle unit 22 and therear of the foot element 24. The connection member 26 can be in avariety of forms such as a connection member, an actuator, a rodconnector, a rigid member, or a piston cylinder. The connection member26 can be operated in a variety of ways, as described by example, inU.S. Pat. No. 7,896,927 and U.S. patent application Ser. No. 12/816,968,each of which is incorporated herein by reference in its entirety.

In use, the prosthetic foot 21 can expand and compress. The prostheticfoot 21 is in expansion when the ankle unit 22 rotates in acounter-clockwise direction about the first movable joint 800A and theconnection member 26 pushes the rear portion of the foot element 24toward an underlying heel element (not shown). The prosthetic foot 21 isin compression when the ankle unit 22 rotates in a clockwise directionabout the first movable joint 800A and the connection member 26 pullsthe rear portion of the foot element 24 upwardly away from the heelelement. The prosthetic foot 21 may be insertable into a foot cover 28as seen in FIG. 10. An example of the prosthetic foot 21 is described ingreater detail in U.S. Pat. No. 9,561,118, and commercially available asthe PRO-FLEX by Össur. This disclosure is incorporated by reference andbelongs to the assignee of this disclosure.

Spacer units of the present disclosure can be adapted for use in one ormore of the movable joints 800A, 800B, or 800C to facilitate assembly,reduce free play in the movable joint, and/or improve the performance ofthe movable joint. For instance, FIG. 11 is a cross-section through themovable joint 800A. The movable joint 800A includes a first component802 comprising an attachment portion 32 of the foot element 24. Thefirst component 802 can include or define a bushing 812 or openingthrough which an axle 808 extends. A second component 804 of the movablejoint 800A is formed by the lower portion of the ankle unit 22. Thesecond component 804 accommodates the axle 808 and receives the firstcomponent 802 between a pair of flanges 34, 36. The first and/or secondcomponents 802, 804 can rotate a pivot point 806 defined by the axle808.

As shown in FIG. 11, the movable joint 800A includes a first gap H1defined between the first component 802 and the flange 34, and a secondgap H2 defined between the first component 802 and the flange 36. Afirst spacer unit 810A is located in the first gap H1 and a secondspacer unit 810B is located in the second gap H2.

The spacer units 810A, 810B can be configured similarly to any of thespacer unit embodiments described herein, such as by including at leastone resilient element formed of an anisotropic material arranged toaccommodate or absorb differences in size of the gaps H1, H2 with littleor no radial expansion. The spacer units 810A, 810B also provide anaxial resistance arranged to help space the first component 802 and thesecond component 804. This provides a simpler and less labor-intensiveassembly of the movable joint 800A and reduces axial play between thefirst and second components 802, 804 without interfering with themovable joint 800A. The spacer units 810A, 810B also can provide anamount of torsional damping as the first and second components 802, 804rotate relative to one another, making the movement of the movable joint800A feel more natural or smooth. Moreover, the spacer units 810A, 810Bcan offer an amount of axial damping if lateral or medial forces aregenerated within the movable joint 800A.

In the illustrated embodiment, the spacer units 810A, 810B can includeone or more rigid elements and at least one resilient element. Forinstance, the spacer units 810A, 810B can include a first rigid elementformed of metal, a second rigid element formed of plastic, a third rigidelement formed of metal, and the resilient element formed of ananisotropic material. The first and third rigid elements can be made ofstainless steel or other suitable metal material. This allows the rigidelements to direct forces away from the resilient element and allows theresilient element to compress and absorb differences or changes in thesize of the gaps H1 or H2. Further, because the resilient element cancompress with little or no expansion in the radial direction, the spacerunits 810A, 810B are less likely to interfere with relative rotationbetween the ankle unit 22 and the foot element 24. Moreover, the rigidelements formed of the metal provide a hard contact surface between thespacer unit and the movable joint to help to provide less wearing in thespacer units 810A, 810B, which, in turn, provides greater stability andsafety to a user.

In other embodiments, the spacer units 810A, 810B can include any numberand or type of elements such as a first rigid element comprising a firstmetal washer, a second rigid element comprising a second metal washer,and the resilient element comprising an anisotropic foam washerpositioned between the first and second rigid elements. In yet otherembodiments, at least one of the spacer units 810A, 810B can include afirst rigid element formed of plastic, a second rigid element formed ofmetal adjacent to the first rigid element, and the resilient elementformed of an anisotropic material adjacent to the second rigid element.Again, this allows the rigid elements to direct forces away from theresilient element and allows the resilient element to compress andabsorb differences or changes in the size of the gaps H1 or H2. Thereduction of parts forming the spacer unit can also help reduce theoverall size and weight of the spacer unit 810A and/or the spacer unit810B.

According to a variation shown in FIG. 12, at least one of the rigidelements 811 can define a groove 813 sized and configured to helpmaintain the position of the resilient element within the spacer unit810A or 810B and/or the gaps H1 or H2.

FIGS. 13 and 14 illustrate a prosthetic system 40 according to yetanother embodiment comprising a shock absorber 41 arranged to provideshock absorption to a prosthetic foot. The shock absorber 41 includes afirst component 902 comprising an outer tube 43 and a second component904 comprising an inner tube 45 and/or bushing 57 that guides movementof the inner tube 45 within the outer tube 43. The inner tube 45 isoperatively connected to a male pyramid 47 and a spring element 49housed within the shock absorber 41. When the shock absorber 41 isloaded and compressed during stance, the inner tube 45 slides toward abottom of the outer tube 43, which, in turn, compresses the springelement 49. When the shock absorber is unloaded and decompressed, storedenergy or spring force in the spring element 49 forces the inner tube 45and the male pyramid 47 back toward their original position.

The inner surface of the outer tube 43 defines a first gap comprising afirst annular groove 51 toward the male pyramid 47 and a second gapcomprising a second annular groove 53 toward a bottom of the outer tube43. A first spacer unit 910A is positioned in the first annular groove51 and a second spacer unit 910B is positioned in the second annulargroove 53. In other embodiments, the spacer units can be positioned inannular grooves formed in the outer surface of the inner tube 45.

The first and second spacer units 910A, 910B comprise resilient elementsin the form of strip elements extending circumferentially around theinner surface of the outer tube 43. The strip elements can be disposedin the first and second annular grooves 51, 53 such that a small or nogap remains between the ends of the strip elements. Like otherembodiments, the resilient elements are arranged to resiliently compressand expand in the first and second annular grooves 51, 53. This helpsthe resilient elements fit in the grooves and reduce play between atleast the outer tube 43 and the bushing 57, simplifying assembly of theshock absorber 41 and improving performance. This is beneficial becausethe bushing 57 and other bushings are known to vary in size due tomanufacturing imperfections and have generally required labor-intensivepractices to ensure a proper fit in prosthetic shock absorbers. Theresilient elements also provide an axial resistance arranged to helpspace the first component 902 and the second component 904.

According to a variation, at least one of the resilient elements caninclude an anisotropic material that can compress in a first directionwith little or no change in shape in a second direction normal to thefirst direction, reducing the likelihood of the resilient elementinterfering with relative movement between the first and secondcomponents 902, 904.

In addition, an engagement between the spacer units 910A, 910B and thebushing 57 can reduce the likelihood of a stick-slip effect during useof the shock absorber 41. The spacer units 910A, 910B can also providean amount of damping in the axial and/or torsional direction. In anembodiment, the damping provided by the spacer units 910A, 910B can beadjustable to isolate or vary the spring force provided by the springelement 49. For instance, a dimension of the spacer units 910A, 910B(e.g., a length or thickness) can be selected to isolate the amount ofdamping provided by the spacer units 910A, 910B from the spring forceprovided by the spring element 49. In other embodiments, a dimension ofthe spacer units 910A, 910B can be selected to isolate the amount ofdamping provided by the spacer units 910A, 910B from bushing 57 guidingmovement of the inner tube 45.

Optionally, the spacer units 910A, 910B can be resistant to lubricantsuch as grease. This allows the spacer units 910A, 910B to keep greaseor other lubricants within a chamber 59 defined within the outer tube 43and along a length between the spacer units 910A, 910B. This isadvantageous over known shock absorbers that have a substantiallysmaller volume (e.g., a single annular groove) for carrying lubricant.As such, the spacer units 910A, 910B help increase the lubricantcapacity of the shock absorber 41, improving lubrication and reducingwear and tear during the life cycle of the shock absorber 41. Further,the resilient elements are arranged to recover and resist permanentdeformation after being compressed over and over during the life cycleof the shock absorber 41, helping to prevent lubricant from undesirablyleaking through the spacer units 910A, and 910B. This also helps theresilient elements eliminate free play between the bushing 57 and theouter tube 43 over the life cycle of the shock absorber 41.

The spacer units 910A, 910B can also be air permeable such that air canbe expelled from the shock absorber 41 via the spacer units 910A, 910Bduring compression of the shock absorber 41. For instance, the spacerunits 910A, 910B can be arranged so that air can move between the endsof the strip elements in the first and second annular grooves 51, 53. Inother embodiments, the spacer units 910A, 910B can be arranged so thatair can move through flow paths defined in the structure of the spacerunits 910A, 910B ensuring smoother operation of the absorber.

FIGS. 15-17 illustrate yet another embodiment of a movable joint 1000for use in a prosthetic or orthopedic system. The movable joint 1000comprises a bearing assembly including a first component 1002 and asecond components 1004 which are arranged to rotate relative to oneanother about at least one pivot point 1006. The pivot point 1006 isdefined by an axle or shaft 1008 extending through the first and secondcomponents 1002, 1004. The first component 1002 comprises a housing 1050and the second component comprises a bearing 1060 that movable couplesthe housing 1050 to the shaft 1008. The movable joint 1000 can beincorporated in a prosthetic foot, a prosthetic ankle, a prostheticknee, or any suitable prosthetic or orthopedic system. As shown best inFIG. 16A, a gap J1 is defined between the bearing 1060 and the housing1050. The gap J1 extends in the radial direction between the bearing1060 and the housing 1050 and on both sides of the bearing 1060 in theaxial direction.

Referring now to FIGS. 16B and 17, a spacer unit 1010 is insertable inthe gap J1 to help maintain the fit between the housing 1050 and thebearing 1060 and position the shaft 1008 and bearing 1060 within thehousing 1050. It will be appreciated that the spacer unit 1010 canincorporate any of the features described herein. The spacer unit 1010includes a resilient element 1011 resiliently compressible andexpandable to controllably vary a thickness of the spacer unit to fillor fit the gap J1.

In an embodiment, the resilient element 1011 can include an anisotropicmaterial arranged to axially compress or expand in the axial directionto fill the gap J1 with little no change in shape in the radialdirection. This allows the spacer unit 1010 to accommodate or absorbchanges in the size of the gap J1 in the axial direction and reduce freeplay between the bearing 1060 and the housing 1050 in both the radialand axial directions. Moreover, the spacer unit 1010 can do so withoutundesirably interfering with the bearing 1060 and/or housing 1050 in theradial direction, facilitating assembly of the movable joint 1000 andimproving its performance.

The spacer unit 1010 can also provide an amount of impact damping to themovable joint 1000. For instance, when the housing 1050 is loaded orimpacted axially, the resilient element 1011 can deform between thehousing 1050 and the bearing 1060 to extract mechanical energy fromaxial movement between the housing 1050 and the bearing 1060, which, inturn, provides axial damping and helps protect the bearing 1060 fromimpact loads on the movable joint 1000 along the shaft 1008. When thehousing 1050 is loaded or impacted radially relative to the shaft 1008,the spacer unit 1010 can be arranged to deform between the housing 1050and the bearing 1060 to extract mechanical energy from radial movementbetween the housing 1050 and the bearing 1060, which, in turn, providesradial damping and likewise helps protect the bearing 1060 fromnon-axial impact loads on the movable joint 1000. This helps improve theoperational life of the bearing 1060 and movable joint 1000.

The spacer unit 1010 may also provide an amount of torsional damping tothe movable joint 1000. When there is relative rotation between thehousing 1050 and at least part of the bearing 1060, at least part of thespacer unit 1010 may resiliently twist and deform to extract mechanicalenergy from the rotational movement between the housing 1050 and thebearing 1060, which, in turn, provides an amount of torsional damping inthe movable joint 1000. According to a variation, the spacer unit 1010can be arranged to provide more motion along a helical axis. Forinstance, as the resilient element 1011 rotates or twist about the shaft1008 or its axis of rotation with the housing 1050, at least a portionof the spacer unit 1010 can be arranged to translate a distance alongthe shaft 1008. By varying the shape and/or properties of the resilientelement 1011, the amount of rotation and/or translation can becontrolled to help define movement within the movable joint 1000. Forinstance, the spacer unit 1010 can be arranged to help the movable joint1000 more closely follow the natural movement of a limb betweendifferent poses (e.g., extreme plantarflexion to extreme dorsiflexion).

Referring to FIGS. 16B and 17, the spacer unit 1010 can have anysuitable shape but is shown having a cylindrical shape arranged to fitwithin a receiving space 1080 formed in the housing 1050. The spacerunit 1010 defines a central opening 1070 arranged to receive the shaft1008, allowing the spacer unit 1010 to be carried on the shaft 1008within the housing 1050. The central opening 1070 includes an annulargroove 1072 that receives and fits over the bearing 1060, a firstdiameter on one side of the annular groove 1072 generally correspondingto an outer diameter of the shaft 1008 and a second diameter on theother side of the annular groove 1072 that is greater than the outerdiameter of the shaft 1008. The second diameter is oversized relative tothe shaft 1008. This advantageously helps heat more easily dissipatefrom the bearing 1060 and facilitates visual inspection of the bearing1060 within the housing 1050.

The outer surface of the spacer unit 1010 includes a circumferentialgroove 1074 extending entirely about the body of the spacer unit 1010and terminating a radial distance from the central opening 1070. Byvarying the depth, shape, and or width of the groove 1074, thecompressibility, stiffness, torsional resistance, damping and/ormovement of the spacer unit 1010 can be controlled. For instance, thegroove 1074 can help isolate movements within the spacer unit 1010 byproviding a clearance to accommodate or facilitate movement of theportion of the spacer unit 1010 engaging the bearing 1060 relative tothe portion of the spacer unit 1010 engaging or adjacent the shaft 1008.This advantageously can help increase the amount of damping provided bythe spacer unit 1010. The resilient element 1011 can be formed ofpolyurethane foam, TPE, EVA, or any other suitable material.

Optionally, the outer surface of the spacer unit 1010 can include atleast one chamfered edge 1082 to help prevent edge loading or stressconcentrations on the spacer unit 1010 within the receiving space 1080of the housing 1050. The movable joint 1000 is shown including onebearing; however, it will be appreciated that the movable joint couldhave two, three, or any suitable number of bearings and the spacer unitor spacer units can be arranged to accommodate the same.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. For instance, while theresilient element embodiments are described to resiliently compress in afirst direction (e.g., axial direction) with little or no expansion in asecond direction normal to the first direction (e.g., radial direction),in other embodiments, the resilient element may compress differently inthe first and second directions. In an embodiment, the resilient elementmay be arranged to resilient compress in the radial direction withlittle or no expansion in the axial direction.

The disclosed embodiments and variations thereof overcome the problemsof prosthetic devices being labor- and cost-intensive to produce becauseof ill-fitting components such as metal washers that need to be grounddown to size or outfitted with additional washers. The embodiments alsoaddress the problem of stick/slip effects in moving parts in prostheticsby providing a resilient element in a spacer unit. The embodiments alsoprovide an improved system that provides axial and radial dampingeffects for improved comfort in prosthetic devices.

The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting. Additionally, thewords “including,” “having,” and variants thereof (e.g., “includes” and“has”) as used herein, including the claims, shall be open-ended andhave the same meaning as the word “comprising” and variants thereof(e.g., “comprise” and “comprises”).

1. A prosthetic system comprising: a movable joint defining at least onegap between first and second components; and at least one spacer unitpositionable in the at least one gap, the at least one spacer unitincluding a resilient element formed of at least one material that iscontrollably deformable to vary a thickness of the at least one spacerunit to fill the at least one gap, and to reduce a likelihood of the atleast one spacer unit interfering with relative movement between thefirst and second components, wherein the at least one material formingthe resilient element is compressible in a first direction with littleor no expansion in a second direction normal to the first direction,said resilient element providing axial resistance by spacing the firstcomponent to the second component.
 2. The prosthetic system of claim 1,wherein the first component comprises an outer tube and the secondcomponent comprises a bushing arranged to guide movement of an innertube within the outer tube, the resilient element reducing play betweenthe outer tube and the bushing.
 3. The prosthetic system of claim 2,wherein the at least one spacer unit includes first and second gaps, aninner surface of the outer tube defines the first gap is formed by afirst annular groove at a first portion of the outer tube and the secondgap is formed by a second annular groove at a second portion at anopposite end of the outer tube from the first portion.
 4. The prostheticsystem of claim 3, wherein the at least one spacer unit includes a firstspacer unit positioned in the first annular groove and a second spacerunit positioned in the second annular groove.
 5. The prosthetic systemof claim 3, wherein the resilient element comprises first and secondstrip elements arranged in the first and second annular grooves definedby an inner surface of the outer tube, respectively.
 6. The prostheticsystem of claim 5, wherein the first and second spacer units arearranged so that air can move between ends of the first and second stripelements in the first and second annular grooves.
 7. The prostheticsystem of claim 5, wherein the first and second strip elements arearranged in the first and second annular grooves so that no gap remainsbetween ends of the first and second strip elements to the first andsecond annular grooves.
 8. The prosthetic system of claim 2, furthercomprising a bushing arranged to guide movement of the inner tube withinthe outer tube, the inner tube being operatively connected to an adapterand a spring element housed within the inner tube and biased against theouter tube.
 9. The prosthetic system of claim 2, wherein the at leastone spacer unit is positioned in annular grooves formed by an outersurface of the inner tube.
 10. The prosthetic system of claim 3, whereinthe resilient element comprises a pair of strip elements arranged inannular grooves defined by an inner surface of the outer tube.
 11. Theprosthetic system of claim 1, wherein the at least one spacer unit isresistant to lubricant or grease.
 12. The prosthetic system of claim 1,wherein the at least one spacer unit is resistant to permanentdeformation.
 13. The prosthetic system of claim 1, wherein the at leastone spacer unit is air permeable.
 14. The prosthetic system of claim 1,wherein the at least one material forming the resilient element is afoam material.
 15. The prosthetic system of claim 1, wherein the atleast one material forming the resilient element is an elastomericmaterial.
 16. A prosthetic system comprising: a movable joint definingat least one gap between first and second components; and at least onespacer unit positionable in the at least one gap, the at least onespacer unit including a resilient element formed of at least onematerial that is controllably deformable to vary a thickness of the atleast one spacer unit to fill the at least one gap, and to reduce alikelihood of the at least one spacer unit interfering with relativemovement between the first and second components, wherein the at leastone material forming the resilient element is compressible in a firstdirection with little or no expansion in a second direction normal tothe first direction; wherein the first component comprises an outer tubeand the second component comprises a bushing arranged to guide movementof an inner tube within the outer tube, the resilient element reducingplay between the outer tube and the bushing, the bushing arranged toguide movement of the inner tube within the outer tube, the inner tubebeing operatively connected to an adapter and a spring element housedwithin the inner tube and biased against the outer sleeve; wherein thefirst component comprises an outer tube and the second componentcomprises a bushing arranged to guide movement of an inner tube withinthe outer tube. wherein the at least one spacer unit includes first andsecond gaps, an inner surface of the outer tube defines the first gap isformed by a first annular groove and the second gap is formed by asecond annular groove directed toward a bottom of the outer tube.wherein the at least one spacer unit includes a first spacer unitpositioned in the first annular groove and a second spacer unitpositioned in the second annular groove; wherein the resilient elementcomprises first and second strip elements arranged in the first andsecond annular grooves defined by an inner surface of the outer tube,respectively.
 17. The prosthetic system of claim 16, wherein the firstand second strip elements are arranged in the first and second annulargrooves so that no gap remains between ends of the first and secondstrip elements to the first and second annular grooves.
 18. Theprosthetic system of claim 16, wherein the at least one spacer unit isresistant to lubricant or grease.
 19. The prosthetic system of claim 16,wherein the at least one spacer unit is resistant to permanentdeformation.
 20. The prosthetic system of claim 16, wherein the at leastone spacer unit is air permeable.